U2 played a not-so-secret free concert Monday afternoon at Empire-Fulton Ferry State Park on the bank of the East River in Brooklyn. For slightly more than an hour, with the Brooklyn Bridge overhead and the lights of downtown Manhattan as a backdrop, the band played songs from its new album, How to Dismantle an Atomic Bomb, and a few older songs to thousands of well-behaved fans ready to shout "Yeah!" or clap along at any cue from Bono.

The concert was the culmination of a well-orchestrated video shoot that doubled as a publicity stunt for the Irish band. Through the afternoon, the four members of U2 were set up on the back of a flatbed truck. They were plugged in and performing the band's next single, All Because of You, as the truck's route wound downtown from the Upper West Side, trailed by a helicopter for aerial shots.

Meanwhile, fans gathered in the state park, largely by word of the Internet. The concert was announced on U2 fan Web sites, like www.interference.com, and a good part of the audience arrived with personalized electronic tickets to an MTV Surprise Performance that didn't specify a band.

The concert will air Dec. 10 as the MTV special mtvJAMMED: U2.